The program being developed under this grant application is to study the mechanisms whereby o-methyl substitution in a specific way enhances the carcinogenicity of arylamines and furthermore, with the naphthalene and biphenyl derivatives, yields chemicals inducing breast and colon cancer in rats. We have synthetized carbon-14-labelled 3-methyl-2-naphthylamine. An additional organic synthesis program deals with the preparation of possible metabolites so that they are available as standards for work on the metabolic fate of the parent compound. We have begun a study of the metabolism of 3-methyl-2-naphthylamine. This effort will be continued with emphasis on the identification and quantification of the metabolites in body fluids. Later, work will deal with the modification of the metabolism as a function of species, strain, and sex, plus environmental factors such as enzyme inducers or inhibitors and the like, to provide a basis for relating metabolism to carcinogenicity and, hopefully, to mechanism.